Nb90W5M5三元固溶体合金的结构和氢渗透性能

合金化是改善Nb金属氢脆问题的有效途径。本文制备了Nb90W5M5三元(M=Co,Ni,Mo,Ti)合金,利用XRD、SEM、PCT、电化学测试和三点弯曲试验研究其相结构、氢化物形成焓、氢扩散系数和机械力学性能。研究证实,Nb90W5M5(M=Co,Ni,Mo,Ti)均为Nb基固溶体结构(Nb-bcc),受原子半径的影响,Nb90W5M5三元合金均有不同程度的晶格畸变现象。Nb90W5Co5合金的晶胞体积畸变收缩明显、晶格点阵常数最小,在Nb基固溶体的晶界和晶内缺陷处有富Co的NbCo化合物固溶组织析出。Nb90W5Co5合金具有低的氢化物形成焓绝对值(-22.3 kJ/mol)、高的氢扩散系数(1.57×10-9 cm^2/s)、高临界载荷(78.4 N),表现出良好的抗弯力学性能和氢渗透性能,这与其多元掺杂导致的微观结构特征有关。

Structure and hydrogen-permeation properties of Nb90W5M5 ternary solid solutions

Alloying is an effective way to solve hydrogen embrittlement of pure Nb.Phase structure,hydride formation enthalpy,hydrogen diffusion coefficient(DH)and mechanical properties of Nb90W5M5(M=Co,Ni,Mo,Ti)alloys have been investigated by XRD,SEM,PCT analysis,electrochemical method and three-point bending test respectively.The results indicated that all Nb90W5M5 samples were solo Nb solid-solution phase(Nb-bcc)and the degree of lattice distortion of these samples was affected by atomic radius of doped element.Bigger crystal cell-volume distortion contraction and the smallest lattice parameter was observed in Nb90W5Co5sample,where Co-rich NbCo solid solution structure was precipitated at grain boundaries and intracrystalline defects of Nb solid solution.Nb90W5Co5sample had lowerabsolute value of hydride formation(-22.3 kJ/mol),higher hydrogen-diffusion coefficient(1.57×10-9 cm^2/s),and higher critical load(78.4 N).Such good bending mechanical properties and hydrogen penetration propertieswererelated to its special microstructure characteristics caused by multiple doping.